这是什么类型的命令：command-name > &! 文档名称

Question

在某处我遇到了具有以下格式的终端命令：

command-name > &! file-name

应该怎么做？

Answer 1

我所知道的唯一有效的 shell> &!是(t)csh. 来自man tcsh：

   > name
   >! name
   >& name
   >&! name
           The  file  name  is used as standard output.  If the file does
           not exist then it is created; if the file exists, it is  trun?
           cated, its previous contents being lost.

           If the shell variable noclobber is set, then the file must not
           exist or be a character special  file  (e.g.,  a  terminal  or
           `/dev/null') or an error results.  This helps prevent acciden?
           tal destruction of files.  In this case the `!' forms  can  be
           used  to suppress this check.  If notempty is given in noclob?
           ber, `>' is  allowed  on  empty  files;  if  ask  is  set,  an
           interacive confirmation is presented, rather than an error.

           The  forms  involving `&' route the diagnostic output into the
           specified file as  well  as  the  standard  output.   name  is
           expanded in the same way as `<' input filenames are.

前任。如果file存在但nofile不存在，那么

$ csh -c 'set noclobber; ls -l file nofile > & outfile'
$ cat outfile
ls: cannot access 'nofile': No such file or directory
-rw-r--r-- 1 steeldriver steeldriver 70 Nov 22 15:10 file

然后

$ csh -c 'set noclobber; ls -l file nofile > & outfile'
outfile: File exists.

但是添加 !

$ csh -c 'set noclobber; ls -l file nofile > &! outfile'

成功。因此!与 中的含义有些相似vi。